**Core Concept**
Lignocaine is a local anesthetic and antiarrhythmic medication that belongs to the class of drugs known as amides. It works by inhibiting the sodium channels in the neuronal membrane, which prevents the initiation and transmission of nerve impulses.

**Why the Correct Answer is Right**
Lignocaine has a rapid onset of action due to its high lipid solubility and ability to cross the blood-brain barrier. It is primarily metabolized by the liver through the cytochrome P450 enzyme system, with a small portion being excreted unchanged in the urine. Lignocaine has a narrow therapeutic index, and its plasma concentration must be carefully monitored to prevent toxicity.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because lignocaine has a relatively short duration of action, typically lasting around 1-2 hours, whereas other local anesthetics like bupivacaine have a longer duration of action.
**Option B:** This option is incorrect because lignocaine is not primarily used as a sedative; it is used to induce anesthesia or to treat arrhythmias.
**Option C:** This option is incorrect because lignocaine is not metabolized by the kidneys; it is primarily metabolized by the liver.

**Clinical Pearl / High-Yield Fact**
Lignocaine's antiarrhythmic effects are most pronounced in the Vaughan-Williams classification as class Ib antiarrhythmic agents, which are characterized by their ability to block sodium channels and reduce automaticity in the heart.

**Correct Answer: A. Lignocaine has a relatively short duration of action, typically lasting around 1-2 hours.**